Infrared detection device

Abstract

An infrared detection device includes a substrate and a heat-type light sensing element. The substrate has a recess, and a frame positioned around the recess. The heat-type light sensing element has a leg and a sensing unit, and the leg is connected onto the frame so that the sensing unit is positioned over the recess. The heat-type light sensing element includes an intermediate layer provided on the substrate, a first electrode layer provided on the intermediate layer, a sensing layer provided on the first electrode layer, and a second electrode layer provided on the sensing layer. The substrate has a linear thermal expansion coefficient larger than that of the sensing layer. The intermediate layer has a linear thermal expansion coefficient decreasing toward the first electrode layer from the substrate.

1 . An infrared detection device comprising:
 a substrate provided with a recess and including a frame positioned around the recess; and   a heat-type light sensing element including a sensing unit and a leg connected onto the frame so that the sensor unit is positioned over the recess, the heat-type light sensing element also including an intermediate layer provided on the substrate, a first electrode layer provided on the intermediate layer, a sensing layer provided on the first electrode layer, and a second electrode layer provided on the sensing layer,   wherein the substrate has a linear thermal expansion coefficient larger than a linear thermal expansion coefficient of the sensing layer, and   wherein the intermediate layer has a linear thermal expansion coefficient decreasing toward the first electrode layer from the substrate.   
     
     
         2 . The infrared detection device according to  claim 1 ,
 wherein one of a polarization amount and capacitance of the sensing layer changes according to temperature change.   
     
     
         3 . The infrared detection device according to  claim 1 ,
 wherein the substrate is formed of a material capable of reflecting infrared rays.   
     
     
         4 . The infrared detection device according to  claim 3 ,
 wherein the substrate is formed of a metallic material.   
     
     
         5 . The infrared detection device according to  claim 4 ,
 wherein the substrate is formed of a rolled steel plate having a minute metallic structure, and   wherein the metallic structure has a diameter smaller than a diameter of the sensing layer that is circular in a top view, and has a diameter smaller than a length of a short side of the sensing layer that is square in a top view.   
     
     
         6 . The infrared detection device according to  claim 1 ,
 wherein two or more elements contained in the substrate diffuse in the intermediate layer.   
     
     
         7 . The infrared detection device according to  claim 6 ,
 wherein the intermediate layer has gradients of diffusion amounts of the two or more elements contained in the substrate, the gradients being different from each other.   
     
     
         8 . The infrared detection device according to  claim 7 ,
 wherein the substrate is formed of a metallic material containing iron and chrome, and   wherein the intermediate layer is formed by diffusion of iron and chrome contained in the substrate.   
     
     
         9 . The infrared detection device according to  claim 6 ,
 wherein the intermediate layer is formed of silicon oxide.   
     
     
         10 . The infrared detection device according to  claim 1 ,
 wherein the heat-type light sensing element is provided on the second electrode layer and further has a constrained layer with a linear thermal expansion coefficient smaller than the linear thermal expansion coefficient of the sensing layer.   
     
     
         11 . The infrared detection device according to  claim 10 ,
 wherein the constrained layer is formed a material capable of absorbing infrared rays, and   wherein the second electrode layer is formed a material capable of reflecting infrared rays.   
     
     
         12 . The infrared detection device according to  claim 11 ,
 wherein expression (1) is satisfied where “d” is a thickness of the constrained layer, “n” is a refractive index of the constrained layer, “λ” is a wavelength of infrared rays as a detection target, and “m” is 0 or a natural number.
     n×d=( 2 m+ 1)×λ/4   (1)
 
   
     
     
         13 . The infrared detection device according to  claim 1 ,
 wherein the second electrode layer is formed of a material capable of absorbing infrared rays.   
     
     
         14 . The infrared detection device according to  claim 1 ,
 wherein the first electrode layer is formed of a perovskite oxide having electric conductivity, and   wherein a ratio of a difference between a lattice constant of a main orientation plane of the first electrode layer and a lattice constant of a main orientation plane of the sensing layer, with respect to the lattice constant of the main orientation plane of the sensing layer falls within ±10%.